Photonic Crystal Simulation

Photonic crystals are periodic structures that are designed to affect the motion of photons in a similar way that periodicity of a semiconductor crystal affects the motion of electrons. The non-existence of propagating EM modes inside the structures at certain frequencies introduces unique optical phenomena such as low-loss-waveguides, omni-directional mirrors and others. The part of the spectrum for which wave propagation is not possible is called the optical band-gap.  The underlying physical phenomenon is based on diffraction. Therefore, the lattice constant of the photonic crystal structure has to be in the same length-scale as half the wavelength of the electromagnetic wave. Figure 1 shows a one dimensional periodic structure which is investigated by using the transient solver of CST MICROWAVE STUDIO® (CST MWS).

1 dimensional periodic structure
Figure 1: 1 dimensional periodic structure

The rods are made from GaAS with refractive index of 3.4 and with an edge length of about 180 nm. The lattice spacing between the rods is 760 nm. As a first step, the transmission of a plane wave through this crystal is simulated.

single column of the array
Figure 2: single column of the array

By using appropriate boundary and symmetry conditions it is sufficient to calculate a single column of this array as shown in Figure 2. In this case, the structure is driven by a waveguide port. Due to the magnetic and electric symmetry planes, the excitation mode is a  normally incident plane wave.

Transmisson vs. wavelength
Figure 3: Transmisson vs. wavelength

Figure 3 shows the transmission through the structure. Between 1400 and 2200 nm the transmission is zero. In this bandgap region no wave propagation in possible.

Wave Propagation at frequencies below the band gap
Figure 4: Wave Propagation at frequencies below the band gap

Figures 4-6 shows the propagation of a plane wave at normal incident for at different frequencies.

Wave propagation at frequencies in the band gap
Figure 5: Wave propagation at frequencies in the band gap

Wave Propagation at frequencies above the band gap
Figure 6: Wave Propagation at frequencies above the band gap

The information obtained about the photonic band gap can be used to design optical devices. Figure 7 shows the periodic PBG structure as described above. A line defect is introduced and the structure is excited with a electromagnetic wave at band gap frequencies. The wave can only propagate inside the line defect.

Photonic Crystal with line defect
Figure 7: Photonic Crystal with line defect

Finally, Figure 8 shows the wave propagation inside the Photonic crystal with a bent defect. Again, the structure is driven with a time harmonic signal. The signal frequency is inside band gap of the crystal. Consequently, the wave propagates inside bend defect.

Photonic crystal with a bend defect
Figure 8: Photonic crystal with a bend defect

This article demonstrates the possibilities to model photonic crystals with CST MWS by using the transient solver. The general characterization would also be possible with the Frequency Domain and Eigenmode Solver of CST MWS by applying periodic boundary conditions.

CST Article "Photonic Crystal Simulation"
last modified 15. Jan 2007 5:42
printed 5. Jul 2015 3:15, Article ID 296

All rights reserved.
Without prior written permission of CST, no part of this publication may be reproduced by any method, be stored or transferred into an electronic data processing system, neither mechanical or by any other method.


25 of 31 people found this article useful

Did you find this article useful?

Other Articles

Modeling Double Negative Materials with CST DESIGN STUDIO™

Modeling Double Negative Materials with CST DESIGN STUDIO™
This paper describes how Double Negative Materials (DNG) material can be simulated in CST MICROWAVE STUDIO® (CST MWS) by using dispersive materials. Read full article..

Designing a Band Notch Filter for a UWB Antenna Using CST MWS

Designing a Band Notch Filter for a UWB Antenna Using CST MWS Document type
Ad Reniers, Technical University Eindhoven High-data-rate wireless communications need wide bandwidths. In the Ultra-Wideband (UWB) frequency band from 3.1 GHz to 10.6 GHz, information may be spread over a large bandwidth at low power levels thus creating the possibility to share the spectrum with other users. To prevent interference with existing wireless systems, like IEEE 802.11a WLAN, stop band characteristics are required from 5 GHz to 6 GHz*. The notch filter function is designed in a low-cost circular planar dipole antenna based on the ‘two-penny’ dipole. To achieve the required specifications for this notch function we used first the CST optimizer. After that we optimized systematic the design. In this presentation we want to show the results of both approaches to achieve a maximum result and try to understand the working of this notch and spur function in this compact UWB antenna. * Paper: Low-cost, compact UWB antenna with frequency band-notch function. H.J. Visser. Read full article..

Simulation Enabling In-flight Connectivity

Simulation Enabling In-flight Connectivity
Webinar recording of the CST Leading Technology Webinar Series 2011 - Mobile phone and wi-fi communication while travelling by air is now being offered by several airlines and will become standard in future. Ensuring a reliable link depends on having properly designed antennas for the in-aircraft picocell base-stations and for the satellite or ground links outside the aircraft. Read full article..

Airbus Defence and Space Uses CST STUDIO SUITE to Analyze Antenna Systems on BepiColombo

Airbus Defence and Space Uses CST STUDIO SUITE to Analyze Antenna Systems on BepiColombo Document type
BepiColombo is a joint mission of the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA). The aim of the mission is to send two orbiters to Mercury in order to study its atmosphere, composition and magnetic field to help understand how the planet was formed, as well as to verify some key predictions of general relativity. Airbus Defence and Space (Airbus DS) is the prime contractor for the ESA elements of the mission, including the Mercury Planetary Orbiter (MPO). The MPO includes multiple antenna systems – some of which are moveable – for telemetry, tracking and control (TTC) and scientific purposes, mounted on a single satellite bus, along with solar panels and instruments which can obstruct the antennas themselves (Figure 1). In order to ensure that the MPO functions as expected when it reaches Mercury’s orbit, Airbus DS has to investigate any possible issues that could affect antenna performance across all of the spacecraft’s different configurations. Read full article..

Calibration of Probes for EMC Near-Field Scanning

Calibration of Probes for EMC Near-Field Scanning Document type
Matthias Spang, University Erlangen-Nuremberg In order to carry out near-field scans of printed circuit boards for EMC investigations, knowledge of the electric and magnetic fields above various calibration boards is necessary. CST Microwave Studio’s transient solver is therefore employed to calculate the near-field patterns on a scanning plane above various microstrip structures. After a spatial 2D-Fourier-transformation, the field values and the measured probe output signals are used to determine the field probe’s receiving characteristics. The results of this calibration process are then verified by applying them on further field measurements with the probe above another microstrip structure and comparing the obtained field strengths with respective simulations again. To obtain a high spatial field resolution, roughly 2.5 million meshcells are used. The frequency band of interest extends from 1MHz up to 3GHz so that great importance is attached to sufficient energy decay. Read full article..
Back Back  

Your session has expired. Redirecting you to the login page...